Manufacture of halo-fluoro derivative of aliphatic hydrocarbons



y 1935- T. MIDGLEY, JR., ET AL 2,007,208

MANUFACTURE OF HALO-FLUORO DERIVATIVE OF ALIPHATIC HYDROCARBQNS FiledFeb. 24, 1951 IN VENT QR S AITORNEB Patented July 9, 1935 UNITED STATESPATENT oFncE I MANUFACTURE OF HALO-FLUORO DERIVA- TIVE OF ALIPHATICHYDROCARBONS Thomas Midgley, Jr., Worthington, Albert L. Henne,Columbus, and Robert Reed McNary, Dayton, Ohio, assignors, by mesneassignments, to General Motors Corporation, a. corporation of DelawareApplication February 24, 1931, Serial No. 517,854

5 Claims.

other than fluorine, which are desired in the final product are alreadypresent in the molecule before fluoration.

Our present invention differs from the former methods in that itsobjects are to fluorate an allphatic hydrocarbon derivative in which allthe halogen atoms desired in the final product are not present beforefluoration, and to add the missing halogen atoms, during or afterfluoration.

As a specific example, CC12F2, can be obtained, according to our presentinvention by fluorating dichloromethane, CHzCl-z to difluoromethane,CHzFz and by subsequently or at the same time chlorinating the CHzFz todichlorodifiuoromethane CClzFz. The latter operation may be modified toform CHClFz or a mixture of CClzFz and CHClFa. A partial fluoration ofCHzCl: to CHzCIF could be subsequently or simultaneously chlorinatedtoCHClzF and/or CChF.

In carrying out this invention, an apparatus similar to thatdiagrammatically shown on the drawing may be used.

A fluorating' substance, such as antimony trifluoride, SbF3, togetherwith a catalytic agent, such as antimony pentachloride, SbCl5, areintroduced into the autoclave 20 through the opening 2|. After theautoclave 20 is closed, a hydrocarbon derivative, such asdichloromethane, CHzClz, which, for convenience, is stored in thetanklZ, is introduce'd'into the autoclave 20 by means-of the pump 23.The reaction then proceeds and may, if desired, be promoted by warmingthe autoclave 20 with a steam jacket 24. One method of obtaining a goodyield of CHzFz is to maintain the pressure at about 130 pounds gauge andthe temperature at about F. The CH2F2 is then admitted into chamber 26where it is chlorinated by chlorine fed through conduit 28. Thechlorination in the reaction chamber 26 is promoted by the iron filings21. The amounts of chlorine and difluorometh ane entering the reactionchamber 26 may be proportionally regulated by means of the valves 29 and25 respectively. The reaction product CC12F2 is led through the conduit30 into the washer 3| containing a solution of sodium hydroxideindicated at 32. where HCl and any excess chlorine are removed.Thereafter the dichloro- 'difluoromethane may be compressed into andstored in the container 33 by means of the pump 34.

The above method of manufacture, and the steps involved therein are setforth in the following equation:

The above specific example has been set forth to illustrate theproduction of CClzFz. However it is possible to also produce a lessfluorated substance in chamber 20, for examplemonochloromonofluoromethane by varying the pressure temperatureconditions within this apparatus. In the reaction chamber 26 thismonochloromonofluoromethane will be halogenated by the chlorine toproduce dichloromonofiuoro or trichloromonofluoromethane according tothe amount of chlorine introduced. The reactions involving theproduction and chlorination of monofluoro compound are as follows:

In the above description, the hologenation takes place after thefiuoration. It is possible, however, to vary the process to carry outboth the fluoration and the halogenation simultaneously. For example,the chlorine may be fed directly into the autoclave 20 and the reactionchamber 26 eliminated. In this manner both the fiuoration andchlorination will be carried out in the autoclave 20. Or, if desired,both processes may be combined. That is, chlorine may be fed into boththe reaction chamber 26 and into the autoclave 20 so as to start thechlorination during fluoration within the autoclave 20 and to bring itto completion in the chamber 26.

Derivatives of methane have been used for illustrative purposes but itis likewise possible to fluorate and subsequently or at the same timehalogenate derivatives of the methane liomologs. Such fiuoro compoundsinclude CHClFz. CClzFz, C2C12F4 illustrative of the ethane series andC3H3F2Bl3 illustrative of the propane series.

In the specific examples, SbFs has been named as the fluorating agentand SbCl5 as the catalytic agent, other fiuorating agents such as leadfluoride and zinc fluoride may be used in place of antimony trifiuorideand other. catalytic agents such as Br, titaniumtetrachloride may beused in place oi. SbCls when an. antimony salt is present.

What is claimed is as follows:

1. The process comprising simultaneously reacting an aliphatichydrocarbon derivative containing hydrogen and halogen other thanfluorine with a fluorating agent and with chlorine, the amount offluorinating agent being insufllcient to cause fluorine substitution onall of the carbon bonds, substituting one or more. fluorine atoms forthe halogen atoms other than fluorine and simultaneously therewithsubstituting one or more chlorine atoms for one of more hydrogen atomsto thereby obtain a halo-fluoro derivative of an aliphatic hydrocarbon.

2. The process which comprises simultaneously reacting the derivative ofmethane containing hydrogen atoms and halogen atoms other than fluorinewith a metal fluoride and with chlorine, the amount of fluorating agen'tbeing insumcient to cause fluorine substitution on all oi the carbonbonds, substituting one or more fluorine atoms for one or more of thehalogen atoms other than fluorine and substituting simultaneously one ormore chlorine atoms for one or more of the hydrogen atoms substantiallyas described to thereby form a halo-fluoro derivative of methane.

3. The process which comprises simultaneously reacting a derivative oi.methane containing hydrogen atoms and halogen atoms other than fluorinewith a fluorating agent and with chlorine, the amount of fluoratingagent being insuflicient to cause fluorine substitution on all 0! thecarbon bonds, substituting one or more fluorine atoms for the halogenatoms other than fluorine and simultaneously therewith substituting oneor more chlorine atoms for one or more hydrogen atoms to thereby form ahalo-fluoro derivative of methane.

all of the carbon bonds, to obtain a halo-fluoro ll hydrocarbonderivative.

THOMAS MIDGLEY, Ja.

ALBERT L. HENNE. ROBERT REED McNARY.

